


Step Kids

by LittleButtonsQueen



Category: Undertale (Video Game)
Genre: Family Feels, Family Fluff
Language: English
Status: Completed
Published: 2017-03-22
Updated: 2017-03-22
Packaged: 2018-10-09 04:27:43
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,989
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10403931
Author URL: https://archiveofourown.org/users/LittleButtonsQueen/pseuds/LittleButtonsQueen
Summary: Basic Fluff of Undertale, Underfell, Swap, and Swap Fell living with Step Children. Mainly fluff





	

**Author's Note:**

> If you guys have any ideas or things you'd like to see let me know  
> Special thanks to Skelltales from tumblr

Swap Fell Sans

Child Age 4  
Day 48 in enemy territory.  
Status of enemy: Not getting dressed

Victory count:  
The Great and Terrible Sans 9  
That Little Shit 9  
Activity of the day: Getting Dressed

   “GET BACK HERE YOU LITTLE SHIT!” Sans screamed as he charged at the child in front of him. As far as Sans was concerned he had already won at least 50% won. The kid was mostly dressed, all he needed was to put on his shoes then he’d toss the brat onto his motorcycle and send the kid off to school.  
   Naturally the child ran out of Sans line of fire, instead running towards the yard… the dirt covered yard… which was currently covered in mud. In the same instant that The Little Shit looked at Sans, and gave him a confident smirk, did Sans figure out his scheme.

  
   “NO! YOU STOP RIGHT THERE!” Sans screeched. In a flash Sans saw a scenario flash before his eyes. His beloved date mate would get a call from The Little Shit’s school saying they were late, AGAIN! His Date Mate would be furious, they’d lose all admiration for him. They’d no longer want to be his Date Mate. “ANTONY PRESTON! GET YOUR FLESHY BUTT AWAY FROM THERE!” Sans growled with newfound determination. THE GREAT AND TERRIBLE SANS wasn’t about to lose the love of his life because of a toddler. His eye began to glow a crimson red, and just at The Little Shit’s foot was about to jump into a large muddy puddle, the boy’s entire body was suddenly frozen mid air.

  
   “Mommy said you can’t use magic!” The boy protested

  
   “Mommy said you can’t use magic” Sans parroted in a mocking tone. “MOMMY WANTS YOU TO GO TO SCHOOL! MOMMY WANTS YOU TO STOP BEING SO DIFFICULT!AND SHE WANTS YOU TO BE CLEAN! AND PUNCTUAL! AND NOT SUCH AN ANNOYING BRAT!!!!!! AND...WHAT’S WITH THAT SMIRK.”  
   

   The little Shit gave Sans his famous smirk and pointed to the clock that hung on the kitchen wall. “It’s eight”  
   Sans glared at the demon child before using his magic to force the child’s feet into his shoes. “THIS ISN’T OVER YOU LITTLE SHIT!”

Little Shit 10  
The great and terrible Sans 9

\------------------------------------------------------------------------------------------------------------------------------------  
   Later that day San’s Date Mate had expressed disappointment, saying with a completely straight face. “Look babe it’s okay if you can’t hand it-”

   “THERE’S NOTHING I, THE GREAT AND TERRIBLE SANS CAN’T HANDLE-”

   “But babe, this is the seventh day in a row Anthony has been late.” His Date Mate gave him a soft look. “Look, I know Anthony can be… difficult, but I’ve already talked to my boss. We’ll change my schedule around-”

   “CHANGE YOUR SCHEDULE?! YOU CAN’T DO THAT! IF YOU GO INTO WORK ANY LATER I’LL NEVER SEE YOU!” Sans hollered. “AS YOUR BOYFRIEND, I FORBID YOU FROM WORKING ANY LATER!”

   His Date Mate gave him a patient smile. “Look babe, I can give you one last chance. But if you can’t get Anthony to school on time, I’m going to have to change my schedule. But don’t worry, we’ll still have weekends...babe”

   By now Sans was fuming. “DATE MATE!” Sans proclaimed with fire burning in his eyes. “AS QUEEN TORIAL IS MY WITNESS THE BOY WILL BE AT SCHOOL BEFORE 8 AM.”

  
\-----------------------

 

   It was 4:45 am when Sans grabbed the boy out of bed. There was some kicking, screaming, meaningless threats, but eventually the boy was dressed. “ALRIGHT YOU LITTLE SHIT. YOUR MOTHER HAS GIVEN ME AN ULTIMATUM. EITHER YOU’RE FLESHY HIDE IS AT SCHOOL BY 8AM OR I’LL NEVER SEE HER AGAIN.”

   The boy smirked.

   Sans smirked right back. “SO I WAS THINKING, SINCE YOU HAVE SO MUCH PENT UP ENERGY IN THE MORNING, I , THE GREAT AND TERRIBLE SANS, HAVE DECIDED THAT YOU NEED MORE EXERCISE.” The room began to glow as two red eyed Gaster Blaster appeared. “WE’RE GOING TO PLAY A LITTLE GAME. IT’S CALLED TAG.”

   For a fraction of a second Sans saw fear in the boy’s eyes, but it was quickly replaced by something else.

   Absolute determination.  
   “Bring it”

\-----------------

   Sans was met that afternoon with kisses, and showered with pure adoration. Which really wasn’t all that surprising, since Sans knew he deserved nothing less from his Date Mate.

   “Sans your AMAZING” His Date Mate cooed “Anthony’s teachers said that not only did he arrived on time, but he behavior was like nothing they had ever seen! He stayed in his seat all day, and even though he took a nap for the last 20 minutes, he was a perfect little angel!” His Date Mate smiled in such a way that Sans felt absolute pride rush into his soul. “How did you do it?”

   “PFF!” Sans huffed “WELL THE BOY TRIED TO PULL HIS USUAL ANTICS, BUT BEING THE GREAT STRATEGIST THAT I AM, I CAREFULLY, THE GREAT AND TERRIFYING SANS, STRATEGIES A PLAN SO CUNNING NOT EVEN THE BOY COULD ESCAPE HIS FATE. DESPITE IT TAKING COUNTLESS ATTEMPT-”

   Sans was silence with a kiss. “Hmm, how did I ever get so lucky to find a guy like you.”

   The rest of Sans night was filled with similar praises.

Sans :10  
The Little Shit: 10

\------

   For the next three months, Sans began his morning in a similar fashion. He’d wake the boy at an ungodly hour and train the boy for a minimum of two hours, feed the child, and promptly drop them off at school.

   For the most part Sans didn’t really tell his Date Mate how he managed to get the boy to school on time; something Sans was grateful for because his Date Mate had been very clear that she didn’t want Sans using magic against their child. Though technically Sans wasn’t using magic against the boy… he was teaching the boy evasive maneuvers… with magic.

   Not that Sans was all that worried. Ever since Sans had begun to train The Little Shit, his behavior at school had been improving. Sans chuckled at the mere thought of the demon child being too tired to territories his teachers. As far as Sans was concerned training the kid had become a win-win for everyone involved in the boy’s life.

   “ANOTHER 5 PUSH UPS AND I’LL THINK ABOUT LETTING YOU HAVE BREAKFAST.” Sans said with a sinister smile plastered onto his face.

   “Pfff! Only five!” The boy challenged. “I’ll do ten!”

   “TRY TWENTY YOU PATHETIC WHELP!”

   “I’LL DO 30!”

    “FINE!”

   “Fine!”

   In the end the boy completed 29, before his arms began to wobble. By that time Sans had shoved a bowl of cereal in his face commanding him to eat. He then proceeded to push the boy onto his motorcycle. Like always the boy tossed his bowl onto the lawn, simply to annoy the skeleton. “YOUR PICKING THAT UP WHEN YOU GET HOME!”

   “Ha good luck making me!”

   The roar of his bike kept Sans from saying anything else. He was almost rid of the brat, then he’d be able to go home and get ready for work, and if his Date Mate’s current mood was any indication, Sans could count on having a very **adult evening.**

   Once at school, the Boy hopped off the bike without saying a word, not that Sans minded. However once the boy was out of sight Sans noticed that the boy had dropped his lunch. Sans grumbled, no doubt his Date Mate would feel so awful that their precious baby hadn’t eaten his lunch that she’d be in no mood for an adult evening.

  
   No the boy had already ruined too many of his evening. He wouldn’t let the boy have a victory simply because the brat was forgetful.

   Sans parked his bike and quickly grabbed the baggie. He stormed in the direction the boy had gone, ready to lecture the boy on the importance of remembering vital supplies, but was stopped.

   “Hey Anthony, who’s the scary bone man?” A child of similar age asked the boy.

   “Oh, that’s my Dad.”  
  
   Anything said after this was a complete blur. All that Sans was sure of was the fact that he threw the boy his lunch before running to his bike.

   He couldn’t explain why buy his soul was pulsing with… joy?

   No, hearing The Boy call him Dad couldn’t fill him with joy. The Little Shit was his mortal enemy, the one force that was not only capable of destroying his relationship with his Date Mate; but also hellbent on making his life difficult.

   “THAT CLEVER LITTLE SHIT!” Sans said “H-HE PLANNED ALL THIS. DROPPING HIS LUNCH! WAITING UNTIL I’D COME BY. ALL SO HE COULD THROW ME OFF MY GAME. HA! I’LL SHOW HIM! MIND GAMES WON’T WORK ON THE GREAT AND TERRIFYING SANS!”

   Bystanders simply looked away as the crazed skeleton cackled.  
\----------------

   Sans waited for what felt like hours. Work had been slow, so Sans had taken advantage and left early. He had called his Date Mate to let her know he’d be picking up the boy. Sans knew he’d have to confront the boy head on. It was the only way to end any attempt the boy had on doing… well honestly Sans wasn’t sure what the boy was planning but Sans was going to put an end to it before the boy could get the upper hand.

   He waited for the boy in his usual spot, for once ignoring the glares of the other human parents. He wasn’t here for the small pathetic fish. Oh no, he was bringing his grill to fry the big one.

   “Monster! Get out of here. We don’t need your kind here scaring off the children.”

   Well, he could fry one little fish.

   However before he could open his mouth something ran towards the angry human. Something demonic. “DON’T TALK TO MY DAD LIKE THAT!” The boy screamed through well placed punches.

   Sans tried his best to not laugh at the sight of a four year old plumbing a grown man, but ultimately failed. It was only when the man attempted to punch back did Sans move.

   Just before the man’s fist came near The Boy’s face it was wrapped in a gloved fist. “YOU KNOW I’M TEMPTED TO LET YOU HIT THE BOY. SOLEY SO I’LL HAVE A REASON TO BASH YOUR WORTHLESS BRAIN INTO THE PAVEMENT. BUT IT WOULD UPSET HIS MOTHER AND I CAN’T HAVE THAT. SO THIS IS YOUR ONLY WARNING.” Sans tightened his grip “IF YOU SO MUCH LOOK AT MY SON I’LL BE USING YOUR SKULL TO HOLD MY TOILET PAPER.”

 -------------------

 

   “Use his skull to hold your toilet paper!” Sans Date Mate said in disbelief. “Are kidding me!”

   Sans held back a giggle, despite his Date Mate being so clearly angry, it was still funny. Still Sans wasn’t stupid and knew now was not the time to point out his comedic genius. Instead Sans focused his sights on the floor in front of him. Every once in awhile he’d mumbled “I’m sorry but for the most part Sans allowed his Date Mate to rant.

   “And you!” His Date Mate said now looking at the boy. “What were you thinking? Fighting a grown man! Why on earth did you think that was a good idea.”

   The boy struck in his chair and muttered a shameful “I dunno”

   Sans’ Date Mate growled in frustration, before sitting on the sofa across from them. “You know the only thing that makes this worse is the fact that you, Sans, are encouraging this behavior.”

   Sans shot up.” WHAT! I DIDN’T TELL HIM TO-”

   “You got him ice cream Sans.”

   “IT WAS TO CONSUL HIM FROM THE CLEAR TRAUMA-”

   His Date Mate lifted a hand, silencing him. “I’m… disappointed in the both of you. You two should be able to ignore a rude person. ” However Sans Date Mate slowly began to smile. ““What am I going to do with you two? “

   “Forgive us?” The Boy said hopefully.

   “Oh Darling of course I forgive you… But your grounded.”

   “WHAT! WHY WOULD YOU DO THAT! “

   “And you’re sleeping on the couch.”

  --------------------

 

   Sans grumbled as he adjusted his blankets. The Little Shit had to have planned this all! Sure The Boy had taken a hit as well, but in the end Sans was forbidden from his own bed. And if his Date Mates mood stayed he’d be forbidden from all adult activities. He huffed as he fixed his pillow, grumbling to himself how he should just kick his Date Mate out of their room.

   “Sans?” A tiny voice called out.

   “WHAT IS IT BOY.” Sans growled.

   The Boy scratched the back of his head before placing a single gummy bear on the living room table. “I’m ...sorry for getting you into trouble. I shouldn’t have punched that guy.”

   Sans scoffed “ DON’T APOLOGIZE, THAT FILTHY HUMAN HAD IT COMING.” A feeling of pride ran through him. “ I’M ALMOST IMPRESSED. YOU DID MANAGE TO KNOCK THE MONGREL DOWN. HEH, YOU MIGHT ACTUALLY HAVE AN OUNCE OF POTENTIAL IN YOU.”

   The Boy smiled at him, making Sans feel something. Though he wasn’t quite sure what it was. “I’ll talk to my Mom when she’s less grumpy. She’s not good at staying mad for long.”

   Sans sat up, had his nonexistent ears deceive him? “A-ARE YOU HELPING ME GET BACK INTO YOUR MOTHER’S GOOD GRACIES?”

   The Boy looked away, gently rubbing his left foot in the carpet.. “Well yeah” The Boy produced to walk back towards his room. “Night Dad”

-9999 damage

  
Victory Count  
Little Shit: 20 maybe even 30  
The Great and Terrible Sans: 10

 

   Sans rolled back onto the couch, and simply listened as The Boy’s door closed. He smiled to himself, knowing that of course any child would love being able to have the privilege of calling the Great and Terrible Sans Dad. Still, to hear it from The Boy … Sans was tempted to count it as a victory, but he’d give this one to The Little Shit.

   “Dad” Sans said gently. “I SUPPOSE THAT’S ACCEPTABLE.”

_______________________________________________________________

Fell Sans

   From the very Sans had heard about his S/O’ s kid he wanted out.

   Not my kid

   But for some reason he stuck around. His S/O was pretty great, and they had made it pretty clear that they didn’t expect him to play Dad to their kid. Which made sense, after all

   Not my kid.

   For the most part the kid was okay. The kid didn’t give him grief, and other than asking for the occasional snack didn’t really ask much from him. Well at least not at first.

   It had started off small. The kid wanting to sit next to him when they watched t.v at night. But slowly the kid started asking for other things. A bedtime story at night. Some time to play ball. They were small request, so he didn’t think anything about it. After all

    Not my kid.

   Then things started moving a bit quick. The kid started waiting for him to come home from work. And the kid would get so damn happy when he’d give the kid the time of day. Sure it was nice, but it … it made him feel things he was pretty sure he didn’t want to feel.

   Still he could deal with all that. Cause the kid was just being friendly, which was a better deal than most in this situation could hope for.

   But than the kid had to ruin it.

   “Is your mom picking you up Leo?”

   “No, my Dad is.”

   Sans didn’t end up picking up the kid that day. His S/O was beyond pissed, but Sans really didn’t care. At least not that night. Instead he spent that afternoon at a bar, mulling over what he heard. And at the end of it all Sans came to the conclusion that he didn’t come into this to be a parent.

   He knew his decision hadn't made his S/O happy. Damn, when he told them Sans was almost certain that they were gonna tell him to get out of their house. But instead they just nodded and said that was fine. They’d be all the parent the kid would ever need.

   Because he’s not your son.

   The kid wasn’t his, so why was he panicking. The kid was here less than three minutes ago. His S/O had gone from calling the kid’s name to just plan screaming it. The other parents had taken notice and many had begun looking around for a lost little boy. The kid had been on the monkey bars, then Sans had made a joke to his S/O and when he looked up the kid was gone.

   “Come on kid.” Sans said to himself, as he left the park and headed to the parking lot. Maybe the kid went back to the car for something. Or maybe he had wondered a bit, not realizing he hadn't told anyone. Sans thought about this morning, the Kid had been wearing a bright red shirt… just like his. The Kid looked like a friken fire hydrant! Why was it so hard to find him?

   “Wait! I changed my mind.” The kid’s voice came from the distance. “I want my Mommy!”

   The next few minutes were a blur. Sans looked over, a van was driving away, and the kid was in the back, looking for someone to help him.  
   

   My kid

   Fury, and fear fueled his magic. Someone was taking his kid, and Sans was about to have A GREAT TIME.

 

    *****************************************************************************************************

   The cops had come pretty quick. The bastard and his van of horrors were gone. Not that Sans really cared. His focus was on the kid. The kid was still pretty shaken up, and was still clinging to him like his life depended on it. “I-I’m s-s-sorry. I d-d-don’t want t-t-to go!!” The kid cried. “I’m s-s-sorry D-Dad.”

  Sans didn’t correct him.

  There was no need to.

   My kid


End file.
